Modern devices tend to be miniaturized. Because a plug is an indispensable element for connecting the electronic devices to the power supplies, designers try to reduce the footprint of the plug. To save space inside electronic devices, conventional foldable plugs usually have three pins, which include two conductive pins and a ground pin. The three pins of the plug are arranged in triangle shape. When the plug is received in the electronic device, the plug occupies large interior space of the device, which increases the overall size of the electronic device and reduces portability of the device.